TRANSFECTION OF MITOCHONDRIA - STRATEGY TOWARDS A GENE-THERAPY OF MITOCHONDRIAL-DNA DISEASES

Successes in classical gene therapies have been achieved by placing a corrected copy of a defective nuclear gene in cells. A similar gene re placement approach for a mutant mitochondrial genome is invariably lin ked to the use of a yet unavailable mitochondrial transfection vector. Here we show that DNA coupled covalently to a short mitochondrial lea der peptide (chimera) can enter mitochondria via the protein import pa thway, opening a new way for gene-, antisense-RNA- or antisense-DNA-de livery in molecular therapies. The import behavior of the purified chi mera, composed of the amino-terminal leader peptide of the rat ornithi ne transcarbamylase (OTC) and a double stranded DNA molecule (17 bp or 322 bp), was tested by incubating with coupled and 'energized' rat ri ver mitochondria in the presence of reticulocyte lysate. The chimera w as translocated with a high efficiency into the matrix of mitochondria utilizing the protein import pathway, independent from the size of it s passenger DNA.